mechanical to electric fans

[cre]

You're not going to free up anything measurable... definitely not 10hp. Also, do note that when you increase the load on the alternator you increase the resistance of the alternator proportionately. And be careful... I don't know why but somehow well over half of the people who do this royally f#$% it up.

100? seems way off whether you're talking Fahrenheit or Celsius. Remember, the thermostat doesn't start to open until around 185?-195?F running them much before that and you'll be loading the engine and adding resistance for no reason (in which case just install a lighter mechanical fan). Engine bay heat isn't going to be a significant issue anytime the car is moving so running the fan, even on low, much before the thermostat's cracking temp doesn't make a whole lot of sense. I probably wouldn't run it until around 170?F and see how things go from there. If the fan moves a lot of air on low you could wait on stepping it up to high speed until 212?F (100?C) or so. This is all going to depend on how and where you drive and also how much air the fan moves at each speed. If you're thinking of the time you'll spend idle waiting in line when at the track between runs then just add another relay and switch to manually bypass the low temp trigger as desired. Data logging the engine temp while driving around for a couple days will help you get this set in no time.